US2015073735A1PendingUtilityA1
Method for adaptive fault location in power system networks
Assignee: UNIV KING FAHD PET & MINERALSPriority: Sep 11, 2013Filed: Sep 11, 2013Published: Mar 12, 2015
Est. expirySep 11, 2033(~7.1 yrs left)· nominal 20-yr term from priority
G01R 31/08Y02E40/70Y04S10/22Y04S10/00G01R 31/088G01R 31/086Y02E60/00
38
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Claims
Abstract
The adaptive fault location method for power system networks utilizes phasor measurement units (PMUs) disposed at disparate locations to obtain synchronized phasor measurements. Three different sets of pre-fault voltage and current phasor measurements are obtained at both terminals of the line under test. The three sets of local PMU measurements at each terminal are used for online calculation of a corresponding system's Thevenin equivalent (TE). This representation of the power system pre-fault network is a reduced two-terminal equivalent. Using the method of multiple measurements with linear regression (MMLR), the three sets of PMU measurements are also employed for online calculation of the transmission line parameters (series resistance, series reactance and shunt susceptance). Online determination of the TEs and line parameters can enhance fault location accuracy by avoiding possible mismatch with the actual parameters due to system loading and other environmental conditions.
Claims
exact text as granted — not AI-modifiedWe claim:
1 . A method for adaptive fault location in a power system network, comprising the steps of:
acquiring a plurality of independent sets of phasor measurement unit (PMU) pre-fault measurements from a first terminal and a second terminal of a line in a power system network; acquiring at least one set of PMU post-fault measurements from the first terminal and from the second terminal; determining the power system network Thevenin equivalents at the first terminal and at the second terminal based on the pre-fault measurements; determining line parameters based on the pre-fault measurements using multiple measurements with linear regression; extracting superimposed electrical measurements using the determined line parameters based on a most recent set of the pre-fault measurements and the post-fault measurements; performing a symmetrical transformation of the superimposed electrical measurements to correspond to a sequence network; determining a sequence source impedance for the first terminal and a sequence source impedance for the second terminal based on the transformed electrical measurements; determining a sequence voltage at the first terminal as a first fault voltage and a sequence voltage at the second terminal as a second fault voltage based on the corresponding determined sequence source impedances and the transformed electrical measurements; and plotting the magnitudes of the determined first fault voltage and second fault voltage along the length of a transmission line between the first terminal and second terminal, wherein a point of intersection between the plotted first fault voltage and the plotted second fault voltage determines the fault distance between at least one of the first terminal and the second terminal and a fault point corresponding to a fault location.
2 . The method for adaptive fault location in a power system network according to claim 1 , further comprising the step of locating a single line to ground (LG) fault type using the determined first and second fault voltages.
3 . The method for adaptive fault location in a power system network according to claim 1 , further comprising the step of locating a line to line (LL) fault type using the determined first and second fault voltages.
4 . The method for adaptive fault location in a power system network according to claim 1 , further comprising the step of locating a line to line to ground (LLG) fault type using the determined first and second fault voltages.
5 . The method for adaptive fault location in a power system network according to claim 1 , further comprising the step of locating a three phase (LLL) fault type using the determined first and second fault voltages.
6 . The method for adaptive fault location in a power system network according to claim 1 , wherein said pre-fault and post-fault phasor measurement acquisition steps comprise obtaining said phasor measurements from Phasor Measurement Units (PMUs) in operable communication with said first and second terminals of said power system network.
7 . The method for adaptive fault location in a power system network according to claim 6 , further comprising the step of using synchronization signals from satellite transmissions of a global positioning system (GPS) to synchronize said acquisition of the pre-fault and the post-fault phasor measurements.
8 . The method for adaptive fault location in a power system network according to claim 1 , further comprising the step of using synchronization signals from satellite transmissions of a global positioning system (GPS) to synchronize said acquisition of the pre-fault and the post-fault phasor measurements.
9 . A method for adaptive fault location in a power system network, comprising the steps of:
acquiring three independent sets of pre-fault voltage and current (V A , I A ) phasor measurements from a first terminal of said power system network; acquiring three independent sets of pre-fault voltage and current (V B , I B ) phasor measurements from a second terminal of said power system network; determining said power system network's Thevenin equivalent at said first terminal from said first terminal pre-fault phasor measurements; determining said power system network's Thevenin equivalent at said second terminal from said second terminal pre-fault phasor measurements; calculating line parameters based on the pre-fault measurements using multiple measurements with linear regression; acquiring a first terminal post-fault voltage and current (V A , I A ) phasor measurement from said first terminal of said power system network; acquiring a second terminal post-fault voltage and current (V B , phasor measurement from said second terminal of said power system network; extracting superimposed electrical measurements based on a most recent set of said pre-fault measurements and said post-fault measurements, said superimposed electrical measurements being transformed to correspond to a sequence network, where: ΔV Ai is an i th sequence of superimposed voltage at said first terminal; ΔV Bi is an i th sequence of superimposed voltage at said second terminal; ΔI Ai is an i th sequence of superimposed current at said first terminal; ΔI Bi is an i th sequence of superimposed current at said second terminal; Z i is an i th sequence impedance of the line between said first and second terminals; Y i is an i th sequence admittance of the line between said first and second terminals; R f is a fault resistance; I fi is an i th sequence of fault current; Z ASi is an i th sequence of equivalent source impedance at said first terminal; Z BSi is an i th sequence of equivalent source impedance at said second terminal; L is a length parameter of a total length of a transmission line between the first terminal and the second terminal; and D is a distance parameter of a distance between at least one said corresponding first terminal or said corresponding second terminal and a fault point F as a fault location; determining a first fault voltage originating from said first terminal (V AFi ) as characterized by the relation:
V
AFi
=
(
Δ
I
Ai
-
Δ
V
Ai
DY
i
)
×
(
(
Z
ASi
1
DY
i
)
+
DZ
i
)
,
where
Z
ASi
=
Δ
V
Ai
Δ
I
Ai
,
determining a second fault voltage originating from said second terminal (V BFi ) as characterized by the relation:
V
BFi
=
(
Δ
I
Bi
-
Δ
V
Bi
(
L
-
D
)
Y
i
)
×
(
(
Z
BSi
1
(
L
-
D
)
Y
i
)
+
(
L
+
D
)
Z
i
)
,
where
Z
BSi
=
Δ
V
Bi
Δ
I
Bi
;
and
determining a point of intersection between a plot of the first fault voltage magnitude |V AFi | and a plot of the second fault voltage magnitude |V BFi | along an entire length of said line L, wherein said point of intersection is the fault location.
10 . The method for adaptive fault location in a power system network according to claim 9 , further comprising the step of locating a single line to ground (LG) fault type using the determined first and second fault voltages.
11 . The method for adaptive fault location in a power system network according to claim 9 , further comprising the step of locating a line to line (LL) fault type using the determined first and second fault voltages.
12 . The method for adaptive fault location in a power system network according to claim 9 , further comprising the step of locating a line to line to ground (LLG) fault type using the determined first and second fault voltages.
13 . The method for adaptive fault location in a power system network according to claim 9 , further comprising the step of locating a three phase (LLL) fault type using the determined first and second fault voltages.
14 . The method for adaptive fault location in a power system network according to claim 9 , wherein said pre-fault and post-fault phasor measurement acquisition steps comprise obtaining said phasor measurements from Phasor Measurement Units (PMUs) in operable communication with said first and second terminals of said power system network.
15 . The method for adaptive fault location in a power system network according to claim 14 , further comprising the step of using synchronization signals from satellite transmissions of a global positioning system (GPS) to synchronize said acquisition of the pre-fault and the post-fault phasor measurements.
16 . The method for adaptive fault location in a power system network according to claim 9 , further comprising the step of using synchronization signals from satellite transmissions of a global positioning system (GPS) to synchronize said acquisition of the pre-fault and the post-fault phasor measurements.Join the waitlist — get patent alerts
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